The heat is probably stored in water by using a simple counter flow heat exchanger. So at night they are using the ‘cool’ ground water for cooling and during the day, they are using the ‘warm’ ground water for heating, probably involving a heat pump.
I’d like to know more details on what they’re storing the heat in, and how the heat exchanger works. Seems like a neat idea though.
The heat is probably stored in water by using a simple counter flow heat exchanger. So at night they are using the ‘cool’ ground water for cooling and during the day, they are using the ‘warm’ ground water for heating, probably involving a heat pump.